Watches and Computers for Spearfishing

Freediving spearfishing computers with depth gauge, dive timer, surface time and logbook. Wrist models in titanium, stainless steel, and polymer, with Bluetooth and GPS.

Computers and Watches for Spearfishing

A wrist computer for spearfishing is a measuring and recording instrument that accompanies the diver during every freedive, providing real-time key data for a safe, aware, and technically controlled spearfishing session. Unlike scuba computers—designed to manage decompression—models dedicated to spearfishing are optimized for monitoring repeated breath-hold dives: they measure current depth, maximum depth reached, dive duration, surface time between one dive and the next, and water temperature, recording the data in an internal logbook that can be analyzed later.

In the Deep Blue Computers category, there are over 20 models available across six specialized brands, with prices ranging from around €115 to over €1,800. This range reflects substantial differences in display technology, case materials, additional functions, wireless connectivity, and certified operating depths. Choosing the right model depends on the level of use and the technical features considered most important.

Types of computers in this category

Deep Blue’s selection includes three main functional categories of wrist instruments for spearfishing:

Entry-level computers with integrated depth gauge: models such as Salvimar One Plus, Salvimar Deeper, and Salvimar Freedive offer the essential functions—current depth, maximum depth, dive time, surface time, temperature—with a fast-refresh depth sensor (0.5 ms in the case of the Freedive) and an internal logbook. They are compact solutions with a user-replaceable battery, suitable for those starting spearfishing or anyone who needs a reliable instrument for days at sea.
Spearfishing computers with advanced functions and Bluetooth connectivity: models such as Cressi King, Cressi Nepto, Mares Smart Apnea, and Mares Sirius Hunter sit in the mid-range. The Sirius Hunter features a 1.3" display with mineral glass and chip-on-glass technology, configurable sequential depth alarms, a logbook with sampling every 0.5 seconds for up to 10 hours of recording, stopwatch, countdown timer, lap counter, and silent mode. Bluetooth connectivity allows dive data to be transferred to a smartphone for analysis via a dedicated app. The Cressi King adds multiple alarm settings and simultaneous display of multiple parameters on the screen.
High-end multifunction computer/watch models: the Garmin Descent line—in the MK3i versions (43mm and 51mm in titanium with DLC Carbon Gray or French Gray coating) and MK3 Inox—and the Garmin Descent G2 AMOLED represent the premium segment. These instruments integrate spearfishing functions within a multisport GPS watch with high-resolution AMOLED or MIP display, navigation, health monitoring, preloaded topographic and marine maps, and compatibility with the Descent T2 wireless transmitter for reading gas pressure during dives. The Suunto Nautic S and Suunto D5 complete the offering in this segment with a robust, streamlined interface designed for underwater use.

These are joined by the H. Dessault Stark Computer, offered at €219, and the Cressi BT Interface accessory for Nepto and King, which enables Bluetooth connection to mobile devices for models that do not include it natively.

How to choose a computer for spearfishing

Choosing a wrist computer for spearfishing depends on a series of practical variables that are useful to evaluate before purchase:

Operating depth: all models in this category are certified for operating depths well beyond the practical limits of recreational spearfishing. The Salvimar Freedive is certified to 100 meters. Garmin Descent and Suunto models operate at even greater depths. This parameter is therefore not a deciding factor for most users, but it is useful to check when used for deep dives.
Depth sensor sampling frequency: a high sampling frequency—0.5 seconds in the Mares Sirius Hunter, 0.5 ms in the Salvimar Freedive—provides a more accurate depth reading during descent and ascent, with greater accuracy for the peak depth recorded in the logbook. This data is relevant for users who rely on the computer to analyze their performance.
Depth alarms: configurable sequential alarms—available for example on the Mares Sirius Hunter—allow acoustic or vibration alert thresholds to be set at predetermined depths. This is a useful function during deep dives or in situations requiring precise control of the depth reached.
Logbook and data analysis: storage capacity and sampling granularity affect the quality of post-session analysis. The Mares Sirius Hunter records up to 10 hours of data with sampling every 0.5 seconds, downloadable via Bluetooth to a smartphone. For those who want to monitor performance progression over time, the availability of a dedicated app (such as Mares/SSI or Garmin Connect) is an important factor.
Display: underwater readability depends on display technology and size. The mineral glass with chip-on-glass technology on the Mares Sirius Hunter offers good readability even in low-light conditions. The AMOLED displays on Garmin Descent G2 models provide high brightness and contrast. The MIP (Memory In Pixel) displays on Garmin Descent MK3 models remain readable even in direct sunlight without excessive battery consumption.
Materials and durability: the titanium case with DLC (Diamond-Like Carbon) coating on Garmin Descent MK3i models offers superior wear resistance and lower weight compared to stainless steel. For intensive use in the marine environment, the corrosion resistance of the case and strap materials is a practical element to consider.
Battery: entry-level and mid-range models use user-replaceable button batteries (CR2450 in the Mares Sirius Hunter), avoiding the cost and inconvenience of replacement service. Garmin and Suunto models use integrated rechargeable batteries, with extended battery life but requiring periodic charging via cable.
Use outside the water: for those who want a single device to wear in everyday life as well, Garmin Descent models integrate multisport GPS functions, sleep tracking, heart rate monitoring, and smartphone notifications. This versatility comes at a higher cost compared to models dedicated exclusively to spearfishing.

Materials and technical features

The computers in the Deep Blue category use different technical solutions according to price range:

Cases and straps: entry-level models (Salvimar, Cressi, and Mares in the lower range) use ABS plastic or high-strength polymer cases with silicone straps, ensuring comfort in the water and resistance to deformation caused by pressure and temperature. Garmin Descent MK3i models use titanium cases with DLC treatment, which reduces surface micro-abrasions, paired with titanium, silicone, or nylon straps depending on the version. The Garmin Descent MK3 Inox uses stainless steel instead.

Lenses: mineral glass—found in models such as the Mares Sirius Hunter—offers greater scratch resistance than organic glass. Garmin MK3 models use sapphire crystal glass in the premium versions, the most scratch-resistant material available in watchmaking.

Depth sensors: all models integrate an absolute pressure sensor for depth calculation. Refresh rate varies between models: values of 0.5 seconds (Mares Sirius Hunter) or 0.5 ms (Salvimar Freedive) indicate high-frequency sampling that increases reading accuracy during the rapid depth changes typical of spearfishing.

Connectivity: Bluetooth is available on Mares Sirius Hunter, Mares Smart Apnea, Cressi King, and Cressi Nepto models (via optional interface). Garmin models integrate ANT+ and Bluetooth for smartphone synchronization and compatibility with external accessories such as the Descent T2 transmitter, which wirelessly transmits gas pressure directly to the wrist.

Battery life: models with a CR2450 button battery do not require charging and provide long battery life in normal use. Garmin models with integrated rechargeable batteries offer stated battery life ranging from several days to weeks in smartwatch mode, with reduced autonomy when GPS mode is active.

Practical use

A wrist computer for spearfishing is useful in all typical spearfishing scenarios. The computer’s functions meet specific operational needs.

During spearfishing, working depths generally fall within a range between 0 and 35 meters. In these contexts, the computer is used mainly to monitor bottom time and surface time, helping respect the necessary intervals between breath-hold dives and reduce the risk of hypoxic blackout. Vibration or acoustic alarms are useful for receiving alerts without taking attention away from the surrounding environment.

The integrated logbook allows retrospective session analysis: maximum depth for each individual dive, duration of each dive, temperature, and overall trend of the day. This data, transferred via Bluetooth to a smartphone on supported models, makes it possible to monitor progress over time and identify patterns in underwater activity.

Available brands

The Deep Blue Computers category includes six brands, each with its own product philosophy:

Garmin is the most represented brand in the category, mainly through the Descent line. Garmin specializes in GPS devices and precision sports electronics: Descent models integrate advanced multisport functions, GPS navigation, preloaded marine maps, and complete connectivity, positioning them at the top end of the market.

Cressi offers the King and Nepto computers, two lines geared respectively toward more complete use (King) and an accessible entry-level solution (Nepto). The optional BT interface allows Bluetooth connectivity to be added to models that do not include it natively. Cressi is a historic Italian underwater brand, with decades of experience in the production of dive instruments.

Mares is represented by the Sirius Hunter and Smart Apnea, both aimed at spearfishing and sport freediving. The Sirius Hunter in particular stands out for its chip-on-glass mineral glass display and advanced logbook functions with fast sampling.

Salvimar covers the entry-level range with the One Plus, Deeper, Deeper Kryptonite, and Freedive models, all featuring accessible prices, essential depth gauge and stopwatch functions, and replaceable batteries. Salvimar is an Italian brand specializing in spearfishing equipment.

Suunto is represented by the Nautic S and D5, two dive watches with a long tradition in the underwater instrument market. The Finnish brand is known for solid construction and a clean, straightforward user interface.

H. Dessault is represented by the Stark model, a mid-range option that enriches the selection with an alternative to the better-known brands.

Conclusion

The Deep Blue Computers category covers the full range of spearfishing needs, from essential digital depth gauges to high-end multisport GPS watches with AMOLED displays and advanced connectivity for users who require a complete wrist instrument in every context.

The presence of brands such as Garmin, Cressi, Mares, Salvimar, Suunto, and H. Dessault ensures broad coverage both in terms of price ranges and construction philosophies. The best choice depends on frequency of use, average working depth, the importance placed on logbook analysis and connectivity, and the preference for a replaceable or rechargeable battery.

For any questions when selecting the most suitable model for your activity, the Deep Blue team is available for personalized technical advice.

Watches and Computers for Spearfishing

Computers and Watches for Spearfishing

Types of computers in this category

How to choose a computer for spearfishing

Materials and technical features

Practical use

Available brands

Conclusion

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